Commission for Instrumentation and Methods of Observation

1
Interoperable Upper-Air Systems
Commission for Instrumentation and Methods of
Observation
November 30, 2005
2
Interoperability

• The ability of an upper-air ground station to fly
  radiosondes made by different manufacturers
• Breaks the hard link between the initial ground
  station investment and follow-on sonde reorders
• Allows for multiple-source bidding for sonde
  reorders
• Prevents users from being stranded with obsolete
  hardware or defunct vendors (e.g. AIR)

3
Technical Issues

• Upper-air sounding systems contain six integrated
  components
• Radiosonde
• Antenna
• Receiver
• Signal processing system (decoder)
• System computer (hardware)
• Met operating system (software)
• For successful interoperability, all elements
  must be compatible

4
RDF Operations
Radiosonde
Signal Processing System (SPS)
System Computer with Met Operating System
Tracking Antenna with 1680 MHz Receiver
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RDF Operations

• Antenna / Receiver
• Uses 1680 MHz carrier to track sonde and generate
  wind data
• Receives coded PTU and passes data to SPS for
  processing

Tracking Antenna
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RDF Operations

• SPS (Decoder)
• Decodes PTU and passes raw data to System
  Computer over serial link

Signal Processing System
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RDF Operations

• Met Software
• Controls RDF antenna
• Applies data corrections
• Calculates wind speed / direction
• Generates met data products
• Manages external communications

System Computer
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RDF Interoperability

• Sonde vendor provides radiosonde and SPS

• Operator uses existing antenna, cables, system
  computer, system software

Radiosonde
Signal Processor
System Computer
Tracking Antenna
9
RDF Compatibility

• Radiosonde Transmitter
• 1680 MHz carrier
• Bandwidth ? 1,000 KHz
• AM or FM modulation

10
RDF Compatibility

• SPS (Decoder)
• Accepts modulated or demodulated PTU data from
  receiver
• Passes serial output to System PC

11
RDF Compatibility

• Met Software
• Selects sonde type and applies appropriate
  corrections
• Delivers consistent met data products regardless
  of sonde used
• Correctly identifies sonde to data users

12
iMet-1500

• Radiosondes in use
• Sippican Mark-II and B-2
• India Met Dept. MK-IV
• InterMet iMet-1
• Field experience
• 24 systems in 15 countries
• Three sonde types making synoptic flights
• IMD testing conversion of 4 systems from IMD
  MK-IV to L-M Sippican Mark-II
• Tanzania evaluation uncovered multiple problems,
  which have been addressed

13
iMet-2000

• Radiosondes in use
• Sippican Mark-IIA
• InterMet iMet-1-BB
• Field experience
• 7 systems in synoptic use
• 90 after program completion

14
403 MHz GPS
Radiosonde
Met Processor (MP)
Antennas (GPS UHF)
System Computer
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403 GPS Operations

• Antennas
• GPS and 403 MHz
• Signals pass through LNAs to receivers

Antennas
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403 GPS Operations

• Met Processor
• Includes GPS/UHF Receivers
• Decodes PTU GPS data
• Programming interface
• Antenna selection logic

Met Processor
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403 GPS Operations

• Met Operating System
• Applies data corrections
• Calculates GPS winds
• Provides programming interface
• Generates met data products
• Manages external communications

System Computer
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GPS Interoperability
Radiosonde
Met Processor
Antennas (GPS UHF)
System Computer
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403 GPS Compatibility

• GPS Antenna
• Standardized, omnidirectional
• Includes LNA
• Should be compatible with multiple receivers

20
403 GPS Compatibility

• UHF Antenna
• Multiple types in use
• Some systems require three
• Some require active switching logic

21
403 GPS Compatibility

• Met Processor
• Receivers specifically designed for antennas and
  LNAs
• May require programming interface
• Highest cost system element

22
403 GPS Compatibility

• Met Operating System
• May require proprietary GPS algorithms
• May require programming interface and calibration
  logic

23
GPS Interoperability

• Worst case situation
• Only System Computer is interchangeable

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RDF vs. GPS

• 1680 MHz RDF
• Sonde vendor provides
• Radiosonde
• Signal processor
• System vendor provides
• Tracking antenna
• Receiver
• Cabling
• System computer
• Met software

• 403 MHz GPS
• Sonde vendor provides
• Radiosonde
• Met processor
• Decoder
• Receivers (GPS/UHF)
• Programming interface
• Met software
• System vendor provides
• Antennas (GPS/UHF)
• Cabling
• System computer